Keyholes from my Forty

[Texas by God]

https://uploads.tapatalk-cdn.com/20230817/7788df9de3b74a2b7a3ef3cad8bf6ee5.jpg
What is causing this? The Lee 40/175 TLTC bullet is PC’d as cast then loaded.
The lower seven clean looking holes were made with 165 gr plated bullets.
Both were loaded below maximum with AA#2 powder and CCI SPM primers.


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[Winger Ed.]

Some have said a few designs of cast & coated boolits just don't like going through a Lee factory crimp die.
Over crimping can do it. If one or two cases were longer than others, it'd give that round too much crimp.

[AlaskaMike]

I can't see the Lee carbide FCD being responsible for this, or over crimping. To cause a bullet to tumble/keyhole means something much more dramatic is happening.

Have you measured the diameter of your PC'd bullets vs the plated ones?

[gpidaho]

Were you holding the pistol like a gangsta when those two rounds were fired? Sorry, couldn't help myself. Gp

[Texas by God]

Were you holding the pistol like a gangsta when those two rounds were fired? Sorry, couldn't help myself. Gp

No, I “sling them overhand” like Jingles did on “Wild Bill Hickok”![emoji3]
Just a bit of normal seating die crimp on these, and I have not measured them for diameter.


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[The Dar]

How far below maximum?

[dondiego]

When I had keyholes it was related to hard alloy, undersized bullets.

[Texas by God]

This is strange.
I fired 6 shots from the smaller magazine and things seemed ok.
Then it went bonkers from the 7 shot magazine….
I got .402” measuring a bullet and the load for this batch was 4.7 grs Bullseye.https://uploads.tapatalk-cdn.com/20230818/612710423b240cfe54929b80a387dfc3.jpg
Perhaps one cavity is bad?
I’ll do some high magnification study on the bullets and mould later on.
In the meantime my .40 is gonna eat Berry’s (I have a bunch!)


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[nvbirdman]

If you're using a Lee FCD it may be sizing your boolit. Load a boolit as normal except without powder then pull the boolit and measure it.

[GhostHawk]

Every time I have had keyholing a larger sized cast bullet cured it.

Ie 9mm .356 keyholed. Bullet 1 grain heavier in .358 or .359 had zero keyholing and a much better pattern.

I've seen this in both pistols and rifles.

The old rule of thumb for cast is 1-3 thousandths bigger than groove. I like 2 or 3 thousandths.

To get big enough in some bullets may mean your going to have issues with the cartridge feeding all the way forward.

As a result I lean towards Truncated cone type bullets or bullets with a significant radius. Giving you the room on the side to chamber without jamming into the rifling.

Chamber cast can be very helpful.

[waksupi]

When I had keyholes it was related to hard alloy, undersized bullets.

yep, yep, yep.

[mdi]

When I had keyholes it was related to hard alloy, undersized bullets.

Yep, too hard and too small are most common causes of destabilizing bullets. And yes, a Lee FCD for handgun calibers can and swage bullets down to undersize diameter (BTDT)...

[Harter66]

I had and XD40 that I cast a bunch of the same bullet in the Varmint 9mm and Hunting 357 , and 45 Colts Rugerish loads alloy at .403 in the .401 groove they key holed well below the 5.8 max load of Unique . Naked and greased that is . I went to WQWW and stopped it . I don't know what the difference is from 35 cal at 35 kpsi and 45 cal at 21-23 kpsi and a 30 kpsi 40 is but the results were round holes all the way up to max loads .

[Texas by God]

So- if the bullet is too hard and under size- would the instability be constant or at random like I’m seeing here?
I don’t use FCD dies at all.


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[Dusty Bannister]

In post #8 you say 6 shots went OK, then changed mags and things went bonkers. If too hard and undersized (specifically undersized) you probably were depositing fouling in the barrel that eventually resulted in wild shooting. Please examine the barrel for lead fouling.

[DougGuy]

OP if you don't have enough throat in the barrel to use whatever diameter boolit you want to use, seated out where it will feed reliably, might want to send the barrel and get it throated. I don't know what model your pistol is, but my 40/10mm carbide reamer still has some life left in it if you have a hardened barrel I could throat it.

[W.R.Buchanan]

I just got thru shooting a bunch of those same boolits thru my Glock last weekend. 5.4 gr of W231 they all ran fine and I had no problems with keyholing. they did smoke the place up though. Mine were sized on the high side of .401 +.0005 because the Lee 6 Cav mold was warping and dropping boolits from .401-.406 and the biggest ones wouldn't even go into the sizing die. It wouldn't swallow any that were bigger than .403 so I had to measure them all, and 50% went back in the pot.

I am going to shoot all these up as soon as my range gets opened again hopefully by Labor Day. I have got a Mihec .402-175 mold that will be used from here on out. Making sure these seal the barrel completely is where I'm at, and also the Berry's 165 gr bullets I've been shooting don't work that well in my Ruger PCC .40 so a little tighter fit might help that?

You never said what gun you were shooting these in?

Randy

[243winxb]

Undersize as cast.

[Texas by God]

I’m using my only .40 pistol; a Shield 40 2.0 that shoots jacketed very well.
I’ll measure the remaining bullets that I have and give them another PC coat perhaps.
Thanks to all.


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[popper]

Undersized and/or soft. You have to look at the bore before firing the sideways one to see the leading. Had that problem yrs ago, shoot several, then oops, several more good then opps again. Bad one cleaned the junk out till it accumulted again. XDm40.

[Blkpwdrbuff]

I size mine at .403 for my Baby Eagle. I don't seem to have any problems.
And it's a polygon barrel, factory.

[Texas by God]

I cleaned the barrel today and there wasn’t any leading to speak of.
I’m going to try it again in cooler weather. I’ll experiment with more coats of PC.
I don’t think that the alloy is the problem. I use it for .38 Special to 38-55 with no problems.


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[BK7saum]

Too soft of an alloy can and will be swaged down, possibly several thousandths, upon seating. I use an expander about 0.005-0.001" under boolit diameter. Bullet diameter is usually 0.001-0.002" over groove diameter or what will chamber freely.

No problems with leading using 9.5 to 10 bhn range scrap in 9mm, 10mm.

Most sizers are 0.002-0.003" under jacketed bullet diameters.

In a .40 with soft alloy, a 0.402 bullet could be swaged down to less than .400 if using a factory die set expander amd a very soft alloy.

.40 amd 10mm cases aren't too bad, but 9mm cases are known to be tough and swage soft boolits.

[waksupi]

You may need to do as I do for .45 acp. Seat the bullet, then crimp in a separate step.

[fredj338]

I can't see the Lee carbide FCD being responsible for this, or over crimping. To cause a bullet to tumble/keyhole means something much more dramatic is happening.

Have you measured the diameter of your PC'd bullets vs the plated ones?

This certainly could happen over crimping if it reduces the bullet dia. I suspect undersized bullets. Though I have seen keyholes with perfectly sized bullets running over certain powders like TG. Odd I know but I have seen it. What is your load data?

[fredj338]

So- if the bullet is too hard and under size- would the instability be constant or at random like I’m seeing here?
I don’t use FCD dies at all.


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Do you size the bullets or shoot as cast? If they are all sized the same then it would constant.